package pociagi;

import java.util.Scanner;

class Wagon{

    Wagon next,prev;
    String id;

    Wagon(String nid)
    {
        id = nid;
        next = prev = null;
    }

}

class Train{

    Train next;
    String id;
    Wagon first,last;
    boolean k;

    Train(String nid)
    {
        id = nid;
        next = null;
        first = last = null;
        k = true;
    }

    public void Reverse()
    {
        if(k == false)
            k = true;
        else
            k = false;
    }

    public void Display()
    {
        if(k == true){
            Wagon A = first;
            do
            {
                System.out.print(A.id + " ");
                A = A.next;

            }while(A != null);
        }
        else
        {
            Wagon A = last;
            do
            {
                System.out.print(A.id + " ");
                A = A.prev;

            }while(A != null);


        }
        System.out.print("\n");

    }

    public void InsertFirst(String TName,String WName)
    {
        Wagon A = new Wagon(WName);
        A.next = first;
        first.prev = A;

        A.prev = null;
        first = A;
    }

    public void InsertLast(String TName,String WName)
    {
        Wagon A = new Wagon(WName);
        last.next = A;
        A.prev = last;
        A.next = null;
        last = A;
    }

}

class Lista{

    Train First;

    Lista()
    {
        First = null;
    }

    public void New(String TName, String WName)
    {

        Train New = new Train(TName);

        New.first = new Wagon(WName);
        New.last = New.first;

        Train tmp = First;
        First = New;
        First.next = tmp;

    }


    public void Display(String TName)
    {
        Train A = Search(TName);
        if(A != null)
        {
            System.out.print(TName + " : ");
            A.Display();
        }
    }

    public void DelTrain(String TName)
    {
        Train A = First;
        if(A.id.compareTo(TName) == 0)
            First = First.next;
        else
            do{

            if(A.next.id.compareTo(TName) == 0)
            {
                A.next = A.next.next;
                break;
            }

            A = A.next;

        }while(A != null);

    }

    public void Union(String TName1, String TName2)
    {
        Train A = Search(TName1), B = Search(TName2);
        if(A != null && B != null)
        {
            A.last.next = B.first;
            B.first.prev = A.last;
            A.last = B.first;
            DelTrain(TName2);
        }
    }

    public void DelFirst(String TName1, String TName2)
    {
       Train A = Search(TName1);
       if(A != null)
           if(A.k == true)
               DelFirst_(A,TName1,TName2);
           else
               DelLast_(A,TName1,TName2);
    }

    public void DelLast(String TName1, String TName2)
    {
       Train A = Search(TName1);
       if(A != null)
           if(A.k == true)
               DelLast_(A,TName1,TName2);
           else
               DelFirst_(A,TName1,TName2);
    }


    public void DelFirst_(Train A, String TName1, String TName2)
    {
            Wagon W = A.first;
            if(A.first.next == null)
                DelTrain(A.id);
            else
            {
                A.first = A.first.next;
                A.first.prev = null;
            }

            New(TName2,W.id);
    }

     public void DelLast_(Train A, String TName1, String TName2)
     {
            Wagon W = A.last;
            if(A.last.prev == null)
                DelTrain(A.id);
            else
            {
                A.last = A.last.prev;
                A.last.next = null;
            }

            New(TName2,W.id);
     }

    public void Reverse(String TName)
    {
       Train A = Search(TName);
       if(A != null)
           A.Reverse();

    }

    public void InsertFirst(String TName, String WName)
    {
       Train A = Search(TName);
       if(A != null)
           if(A.k == true)
            A.InsertFirst(TName,WName);
           else
            A.InsertLast(TName,WName);

    }

    public void InsertLast(String TName, String WName)
    {
       Train A = Search(TName);
       if(A != null)
           if(A.k == false)
            A.InsertLast(TName,WName);
           else
            A.InsertFirst(TName, WName);
    }

    public Train Search(String TName)
    {
        Train A = First;
        if(A != null)
        do{

            if( A.id.compareTo(TName) == 0 )
                return A;
            A = A.next;

        }while(A != null);

        return null;
    }


}

public class Source {

    public static Scanner input = new Scanner (System.in);

    public static void main(String[] args) {

        int z = input.nextInt();

        Lista A = new Lista();

        A.New("T1", "W1");
        A.InsertLast("T1","W2");
        A.Display( "T1"  );
        A.InsertFirst( "T1", "W0" );
        A.Display( "T1"  );
        A.Reverse("T1");
        A.Display("T1");
        A.InsertFirst("T1", "Z1");
        A.Display("T1");
        A.Reverse("T1");
        A.Display("T1");

/*
        A.DelFirst("T1", "T2");
A.Display("T1");
A.Display("T2");
A.DelLast("T1", "T3");
A.Display("T1");
A.Display("T3");
*/
/*
A.New("T1", "W1");
A.InsertLast("T1","W2");
A.Display( "T1"  );
A.InsertFirst( "T1", "W0" );
A.Display( "T1"  );
A.DelFirst("T1", "T2");
A.Display("T1");
A.Display("T2");
A.DelLast("T1", "T3");
A.Display("T1");
A.Display("T3");
System.out.println("--------");
A.InsertFirst("T3","h1");
A.Display("T3");
A.InsertLast("T3","h2");
A.Display("T3");
A.InsertFirst("T3","j1");
A.Display("T3");
A.Reverse("T3");
A.Display("T3");
A.Union("T1","T3");
A.Display("T1");
A.Reverse("T1");
A.Display("T1");
*/        /*
        for(int j = 0 ; j < z ; j++)
        {
            int n = input.nextInt();
            String polecenie = input.nextLine();
            for(int k = 0 ; k < n ; k++)
            {



            }

        }

*/

    }

}